Physiology Block 3 Week 17 19 Exercise

Question 1

Essential aspects in mobilization

Answer 1

communication, energy production, and transportation.

a) the brain must stimulate muscles for coordinated contractions
b) fuel must be made available for the energy needed for muscle contractions
c) oxygen must be provided and waste products must be eliminated.

Question 2

Where do commands for voluntary movement originate from?

Answer 2

Cortical associate areas

Question 3

What parts of the brain plan voluntary movements?

Answer 3

The cortex, basal ganglia, and cerebellum work cooperatively to plan movements.

Basal ganglia and cerebellum are part of a feedback circuit concerned with planning and organizing voluntary movement

Question 4

What feedback does the cerebellum provide in movements?

Answer 4

Feedback to adjust and smooth movements

Question 5

How are movements from the cortex relayed to muscles?

Answer 5

Executed by the motor cortex thru impulses via corticospinal tracts to spinal motor neurons

Question 6

Supplementary motor area

Answer 6

involved in organizing or planning particularly complex movement.

Question 7

Premotor area

Answer 7

setting posture at the start of movement or in control of proximal limb muscles needed to orient the body for movement.

Question 8

How is the complexity of movement distributed amongst the areas of the cortex?

Answer 8

31% of corticospinal tract neurons are from the primary motor cortex

29% from the premotor and supplementary motor cortex

the remaining 40% from neurons in the primary somatic sensory cortex and posterior parietal cortex

This distribution is indicative of the complexity and multiple muscles that need to be activated for coordinated/smooth movements.

Question 9

Regions of the human cerebral cortex and other areas concerned with control of voluntary movement

Answer 9

Prefrontal Cortex

Premotor Cortex

Supplementary Motor Area

Motor Cortex

Primary Somatic Sensory Cortex

Posterior Parietal Cortex

Question 10

Damage to cerebellum leads to?

Answer 10

Ataxia and tremors

Cerebellum provides coordinated muscle activity through input from the contracting muscles and then relaying signals to the primary motor cortex

Question 11

Basal ganglia are composed of several nuclei and three major biochemical pathways that influence the motor cortex via thalamus

Answer 11

Dopaminergic
Cholinergic
GABAergic

Disease of these pathways lead to hyperkietic (Parkinson’s) or hypokinetic muscle conditions

Question 12

How can contractile muscle strength be increased?

Answer 12

Contractile muscle strength
can be increased by increasing muscle size through exercise training programs and through the action of anabolic steroids such as testosterone.

Question 13

Work performed by muscles

Answer 13

Force applied x distance force applied

Question 14

Power vs strength

Answer 14

Power is work over period of time

Question 15

Is power output greater during a 100 m dash or running a mile?

Answer 15

100 m dash

Maximal power out declines with duration of muscle contraction

Question 16

Endurance

Answer 16

time a task can be sustained before exhaustion

Determinant of endurance is glycogen stores in muscle from one’s diet

High carb diet: high glycogen stores (40 g/Kg)
Mixed diet: 20 g/Kg
High fat: 6g/Kg

Question 17

Why is ATP a good source of energy?

Answer 17

• The last 2 phosphate bonds are high energy
• Only good for 3 seconds of maximal muscle power
• need continuous supply of ATP

Question 18

Phosphocreatine

Answer 18

Broken down into creatine and phosphate

Muscles have 2-4x more stored than ATP

Question 19

Phosophagen Energy System

Answer 19

Phosphocreatine and ATP energy storage

Sufficient to provide E for a power event like 100m dash

Question 20

Glycogen-Lactic Acid System

Answer 20

Anaerobic Metabolism: If oxygen is not available, pyruvic acid is converted to lactic acid which diffuses out of the muscle.

Maximum muscle activity for about 1.5 minutes

Important at work rates greater than about 60% of maximal oxygen consumption

Question 21

How are high work rates achieved?

Answer 21

Oxygen consumption is proportional to the work load, but there is a maximal capability to provide energy through the oxidative pathway

High work rates are achieved by large increases in contribution from the lactic acid pathway

Question 22

Aerobic System

Answer 22

oxidation of foodstuffs in mitochondria where glucose, fatty acids, and amino acids are broken down to release energy and form ATP

Supply energy as long as nutrients are available
–provides for endurance of the muscles.

The oxidative pathway provides 32 ATP molecules/molecule of glucose.

Availability of nutrients is enhanced by increased epinephrine during exercise thereby increasing glucose output from the liver and fatty acid output from adipose tissue.

Question 23

Relative Moles of ATP generated

Phosphagen System
Glycogen-Lactic Acid System
Aerobic System

Answer 23

Phosphagen System: 4
Glycogen-Lactic Acid System: 2.5
Aerobic System: 1

Question 24

Oxygen Debt

Answer 24

Oxygen consumption remains elevated after exercise to reconstitute (build up) the phosphagen system and convert lactic acid to glucose.

Question 25

As work rate increases, what happens to: - VO2 - CO - HR - SV

Answer 25

VO2, CO, and HR increase linearly until 60% of maximal exercise due to max SV Thus, further increases in cardiac output are dependent on increases in heart rate

Question 26

During exercise, what happens to blood pressure and TPR?

Answer 26

Systolic: Large Increases Diastolic: very small increase TPR: Dramatic decrease The increase in systolic pressure and decrease in TPR is from vasodilation increasing flow to the muscles Rhythmic due to capillary compression during muscle contraction

Question 27

How does CO (flow) to change from rest to exercise in: - muscle - brain - abdomen - kidney - skin - heart

Answer 27

Increased: Muscle Decreased: Brain, Abdomen, Kidney Unchanged: Skin and Heart

Question 28

Exercise Centers

Answer 28

In the cerebral cortex Increase sympathetic/ dec parasympathetic output to the heart and blood vessels Increase baroreceptor reflex set point via the medullary cardiovascular nuclei ***symp vasoconstriction to non-exercising vascular beds (GI and Kidneys) ***local vasodilation in muscles

Question 29

During exercise, how does ventilation change at: - -up to 60% max - -intense exercise - -low work rate

Answer 29

60% max: ventilation increases in proportion to metabolic rate High intensity exercise: hyperventilation--indicates increasing more than metabolic rate Low work rate: increased ventilation due to increased tidal volume --more fresh air to lungs with each breath (decreased dead space: tidal volume) At high TV, lung compliance decreases --to increase ventilation, increase breathing frequency

Question 30

Exercise on arterial blood gases

Answer 30

Signal for hypercapnea not from increased stimulation of carotid and intracranial chemoreceptors Above 60% max: lacacidosis and hyperventilation

Question 31

Ventilation (atmospheric to alveolar gas exchange) and Diffusion (alveolar to capillary gas exchange) increases with exercise

Answer 31

The increase in diffusion is due to recruitment of alveolar capillary units which increases the surface area for gas exchange. The increase in the alveolar-capillary PO2 difference at high workloads = hyperventilation and failure of diffusing capacity to increase by the same amount. The increase in PAO2 provides increased driving pressure for diffusion of oxygen.

Question 32

Why is pulmonary capillary dilation important in exercise?

Answer 32

The need for gas exchange is greatly increased since arterial-venous (mixed venous) PO2 difference increases --Exercise MV PO2 << Rest MV PO2 The pulmonary capillaries will dilate so blood remains in lung for longer duration for more extraction

Question 33

What causes greater extraction of oxygen during exercise to tissues?

Answer 33

This greater extraction of oxygen during exercise is a result of decreased hemoglobin affinity for oxygen Increases the driving pressure of oxygen from the capillaries to the tissue Vasodilation in the muscles causes a greater cardiac output delivered to tissues with a high metabolic rate

Question 34

How much energy released by ATP during exercise is converted to work?

Answer 34

25%, therefore 75% converted into heat The body will retain some heat and allow the body temp to increase

Question 35

Ways to lose heat

Answer 35

Vasodilation of arterioles in the skin Sweating (increased symp innervation to sweat glands) Temperature controlled by thermoreceptors in skin (environmental temp) and hypothalamus (body temp) Hydration and electrolyte balance

Question 36

Neuroendocrine responses to exercise

Answer 36

Increased GH and cortisol after exercise --tissue repair Catecholamines (Epi and NE) --liver release of glucose and adipose release of fatty acid to maintain ATP (glucagon); suppressed insulin Opiods (endorphins) --runner's high

Question 37

What contributes to increasing maximal oxygen consumption during physical training?

Answer 37

The amount of increase is related to the intensity and duration of the exercise program Contributing to the increase in maximum oxygen consumption: -Increased CO secondary to increased in SV and HR - Enhanced heart performance due to: - -increase muscle and myocyte site - -increased vascularization Increased vascularization of skeletal muscle: - -enhances delivery of blood - -reduce the distance for gas diffusion between vasculature and muscle Training enhances endocrine, thermoregulatory, and metabolic responses - -enhance mobilization of glucose and fatty acids - -elimination of heat

Question 38

Does training enhance the respiratory system?

Answer 38

Other than training of the respiratory muscles, there is little evidence that training enhances the respiratory system.

Question 39

Limiting Factors to maximal oxygen consumption

Answer 39

Cardiovascular system's capability to deliver oxygen Capability of muscle to extract oxygen Respiratory muscles "steal oxygen" from locomotor muscles

Question 40

Fatigue

Answer 40

Fatigue limiting work performance is a decrease in work capacity due to work itself. Also induced by (mental) boredom/staleness, drugs, and illness. 8 hours of office work fatigue is different from 8 hours of heavy construction work Physical fatigue can be due to: a) depletion of energy stores b) accumulation of metabolic waste products c) breakdown of homeostasis Potential sites of work induced fatigue include the: a) muscle fiber b) motor nerve and end plate c) synapses within ganglia d) the nerve cell body e) sensory nerve ending Motivation--limitations to exercise performance are dependent to some extent on tolerating and/or suppress sensations of fatigue and/or pain

Question 41

Which of the following statements regarding the signal for limb movement during muscular exercise is INCORRECT? the cerebral cortex, basal ganglia, and cerebellum collaborate to plan the movement. the signal for the movement is relayed from the brain to the muscles through the corticospinal tract. the cerebellum provides feedback to the motor cortex to adjust and smooth movement. the primary motor cortex is the site from which all movement originates. dopaminergic, cholinergic, and GABAergic systems in the basal ganglia influence the motor cortex through the thalamus.

Answer 41

the primary motor cortex is the site from which all movement originates Pre-motor, motor, and intermediate cerebellum

Question 42

A high carbohydrate diet would be most beneficial to which of the following? An Olympic sprinter running 100 meters. A weight lifter competing in the Olympics. An emphysema patient fishing in a trout stream. A middle-aged man running the Boston marathon. A farmer with interstitial lung disease driving a tractor.

Answer 42

A middle-aged man running the Boston marathon.

Question 43

Which of the following would be expected to decrease as a healthy untrained person undergoes an exercise-training program? ``` Resting stroke volume Resting cardiac output Resting heart rate Maximal oxygen uptake Maximal alveolar ventilation ```

Answer 43

Resting heart rate